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<Title>Track Line with Axis Labels</Title>
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<p class="heading0">ChartDirector 7.0 (Java Edition)</p>
<p class="heading1">Track Line with Axis Labels</p>
<hr class="separator">
<div class="content"><img src="images/trackaxis_web.png" width='675' height='405'><br><br>
This sample program demonstrates a track cursor programmed with the following features:<br><br>
<ul>
<li>A vertical line that connects the data points to the x-axis, with an x-axis label displaying the x value.<br><br>
<li>Horizontal lines that connect the data points to the y-axes, with y-axis labels displaying their values.<br></ul>
On the server side, the code draws the chart as usual, and outputs both the image and the <a href="jschartmodel.htm">Javascript Chart Model</a> of the chart.<br><br>
The <b>trackLineAxis</b> Javascript function is the routine that draws the track cursor. Its key elements are:<br><br>
<ul>
<li>The code first uses <a href="JsChartViewer.hideObj.htm">JsChartViewer.hideObj</a> to clear the previous track cursor, if any.<br><br>
<li>The nearest x data value is obtained using <a href="JsXYChart.getNearestXValue.htm">JsXYChart.getNearestXValue</a>.<br><br>
<li>The code iterates through all data sets in all layers to find the highest data point at the nearest x data value. It then draws a vertical line from that point to the x-axis using <a href="JsChartViewer.drawVLine.htm">JsChartViewer.drawVLine</a>, and the corresponding x-axis label using <a href="JsChartViewer.showTextBox.htm">JsChartViewer.showTextBox</a>.<br><br>
<li>The code iterates through all data sets in all layers once more to find all the data points at the nearest x data value. For each of these points, it draws a horizontal line to connect the point to the y-axis using <a href="JsChartViewer.drawHLine.htm">JsChartViewer.drawHLine</a>, draws the axis label using <a href="JsChartViewer.showTextBox.htm">JsChartViewer.showTextBox</a>, and draws a square dot at the point using <a href="JsChartViewer.showTextBox.htm">JsChartViewer.showTextBox</a> and <a href="JsChartViewer.htmlRect.htm">JsChartViewer.htmlRect</a>.<br></ul>
</div><p class="heading1a">Source Code Listing</p><div class="content">
<b>[JSP Version]</b> jspdemo/trackaxis.jsp
<div class='codeblock'><code class='pre'>&lt;%@page import="ChartDirector.*, java.util.*" %&gt;
&lt;%
// Data for the chart as 2 random data series
RanSeries r = new RanSeries(127);
double[] data0 = r.getSeries(180, 10, -1.5, 1.5);
double[] data1 = r.getSeries(180, 150, -15, 15);
Date[] timeStamps = r.getDateSeries(180, new GregorianCalendar(2011, 0, 1).getTime(), 86400);

// Create a XYChart object of size 670 x 400 pixels
XYChart c = new XYChart(670, 400);

// Add a title to the chart using 18pt Times New Roman Bold Italic font
c.addTitle("Plasma Stabilizer Energy Usage", "Times New Roman Bold Italic", 18);

// Set the plotarea at (50, 55) with width 100 pixels less than chart width, and height 90 pixels
// less than chart height. Use a vertical gradient from light blue (f0f6ff) to sky blue (a0c0ff) as
// background. Set border to transparent and grid lines to white (ffffff).
c.setPlotArea(50, 55, c.getWidth() - 100, c.getHeight() - 90, c.linearGradientColor(0, 55, 0,
    c.getHeight() - 35, 0xf0f6ff, 0xa0c0ff), -1, Chart.Transparent, 0xffffff, 0xffffff);

// Add a legend box at (50, 25) using horizontal layout. Use 10pt Arial Bold as font. Set the
// background and border color to Transparent.
c.addLegend(50, 25, false, "Arial Bold", 10).setBackground(Chart.Transparent);

// Set axis label style to 8pt Arial Bold
c.xAxis().setLabelStyle("Arial Bold", 8);
c.yAxis().setLabelStyle("Arial Bold", 8);
c.yAxis2().setLabelStyle("Arial Bold", 8);

// Set the axis stem to transparent
c.xAxis().setColors(Chart.Transparent);
c.yAxis().setColors(Chart.Transparent);
c.yAxis2().setColors(Chart.Transparent);

// Configure x-axis label format
c.xAxis().setMultiFormat(Chart.StartOfYearFilter(), "{value|mm/yyyy} ", Chart.StartOfMonthFilter(),
    "{value|mm}");

// Add axis title using 10pt Arial Bold Italic font
c.yAxis().setTitle("Power Usage (Watt)", "Arial Bold Italic", 10);
c.yAxis2().setTitle("Effective Load (kg)", "Arial Bold Italic", 10);

// Add a line layer to the chart using a line width of 2 pixels.
LineLayer layer = c.addLineLayer2();
layer.setLineWidth(2);

// Add 2 data series to the line layer
layer.setXData(timeStamps);
layer.addDataSet(data0, 0xcc0000, "Power Usage");
layer.addDataSet(data1, 0x008800, "Effective Load").setUseYAxis2();

// Create the WebChartViewer object
WebChartViewer viewer = new WebChartViewer(request, "chart1");

// Output the chart
viewer.setChart(c, Chart.SVG);

// Output Javascript chart model to the browser to support tracking cursor
viewer.setChartModel(c.getJsChartModel());
%&gt;
&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;head&gt;
    &lt;title&gt;Track Line with Axis Labels&lt;/title&gt;
    &lt;script type="text/javascript" src="cdjcv.js"&gt;&lt;/script&gt;
&lt;/head&gt;
&lt;body style="margin:5px 0px 0px 5px"&gt;
&lt;script type="text/javascript"&gt;

//
// Use the window load event to set up the MouseMovePlotArea event handler
//
JsChartViewer.addEventListener(window, 'load', function() {
    var viewer = JsChartViewer.get('&lt;%=viewer.getId()%&gt;');

    // Draw track cursor when mouse is moving over plotarea. Hide it when mouse leaves plot area.
    viewer.attachHandler(["MouseMovePlotArea", "TouchStartPlotArea", "TouchMovePlotArea", "ChartMove"],
    function(e) {
        this.preventDefault(e);   // Prevent the browser from using touch events for other actions
        trackLineAxis(viewer, viewer.getPlotAreaMouseX());
        viewer.setAutoHide("all", ["MouseOutPlotArea", "TouchEndPlotArea"]);
    });
});

//
// Draw track line with axis labels
//
function trackLineAxis(viewer, mouseX)
{
    // Remove all previously drawn tracking object
    viewer.hideObj("all");

    // The chart and its plot area
    var c = viewer.getChart();
    var plotArea = c.getPlotArea();

    // Get the data x-value that is nearest to the mouse, and find its pixel coordinate.
    var xValue = c.getNearestXValue(mouseX);
    var xCoor = c.getXCoor(xValue);

    // The vertical track line is drawn up to the highest data point (the point with smallest
    // y-coordinate). We need to iterate all datasets in all layers to determine where it is.
    var minY = plotArea.getBottomY();

    // Iterate through all layers to find the highest data point
    for (var i = 0; i &lt; c.getLayerCount(); ++i)
    {
        var layer = c.getLayerByZ(i);

        // The data array index of the x-value
        var xIndex = layer.getXIndexOf(xValue);

        // Iterate through all the data sets in the layer
        for (var j = 0; j &lt; layer.getDataSetCount(); ++j)
        {
            var dataSet = layer.getDataSetByZ(j);
            var yCoor = c.getYCoor(dataSet.getPosition(xIndex), dataSet.getUseYAxis());
            if ((yCoor != null) &amp;&amp; (dataSet.getDataColor() != null))
                minY = Math.min(minY, yCoor);
        }
    }

    // Draw a vertical track line at the x-position up to the highest data point.
    viewer.drawVLine("trackLine", xCoor, Math.max(minY, plotArea.getTopY()),
        plotArea.getBottomY() + 3, "black 1px dotted");

    // Draw a label on the x-axis to show the track line position
    viewer.showTextBox("xAxisLabel", xCoor, plotArea.getBottomY() + 3, JsChartViewer.Top,
        c.xAxis().getFormattedLabel(xValue, "mmm dd, yyyy"),
        "font:bold 11px Arial;color:#FFFFFF;background-color:#000000;padding:2px 3px");

    // Iterate through all layers to draw the axis labels for the data points
    for (var i = 0; i &lt; c.getLayerCount(); ++i)
    {
      var layer = c.getLayerByZ(i);

        // The data array index of the x-value
        var xIndex = layer.getXIndexOf(xValue);

        // Iterate through all the data sets in the layer
        for (var j = 0; j &lt; layer.getDataSetCount(); ++j)
        {
            var dataSet = layer.getDataSetByZ(j);

            // The positional value, axis binding, pixel coordinate and color of the data point.
            var dataPoint = dataSet.getPosition(xIndex);
            var yAxis = dataSet.getUseYAxis();
            var yCoor = c.getYCoor(dataPoint, yAxis);
            var color = dataSet.getDataColor();

            // Draw the axis label only for visible data points of named data sets
            if ((yCoor != null) &amp;&amp; (yCoor &gt;= plotArea.getTopY()) &amp;&amp; (yCoor &lt;= plotArea.getBottomY()) &amp;&amp;
                (color != null))
            {
                // The axis label consists of 3 parts - a track dot for the data point, an axis label,
                // and a line joining the track dot to the axis label.

                // Draw the line first. The end point of the line at the axis label side depends on
                // whether the label is at the left or right side of the axis (that is, on whether
                // the axis is on the left or right side of the plot area).
                var xPos = yAxis.getX() + ((yAxis.getAlignment() == JsChartViewer.Left) ? -4 : 4);
                viewer.drawHLine("joinLine" + i + "_" + j, yCoor, xPos, xCoor, color + " 1px dotted");

                // Draw the axis label. If the axis is on the left side of the plot area, the labels
                // should right aligned to the axis, and vice versa.
                viewer.showTextBox("yAxisLabel" + i + "_" + j, xPos, yCoor,
                    (yAxis.getAlignment() == JsChartViewer.Left) ? JsChartViewer.Right : JsChartViewer.Left,
                    dataPoint.toPrecision(4), "padding:2px 3px;font:bold 11px Arial;background-color:" +
                    color + ";color:#FFFFFF;-webkit-text-size-adjust:100%;");

                // Draw the track dot
                viewer.showTextBox("dataPoint" + i + "_" + j, xCoor, yCoor, JsChartViewer.Center,
                    viewer.htmlRect(7, 7, color));
            }
        }
    }
}

&lt;/script&gt;
&lt;div style="font-size:18pt; font-family:verdana; font-weight:bold"&gt;
    Track Line with Axis Labels
&lt;/div&gt;
&lt;hr style="border:solid 1px #000080" /&gt;
&lt;div style="font-size:10pt; font-family:verdana; margin-bottom:1.5em"&gt;
    &lt;a href="viewsource.jsp?file=&lt;%=request.getServletPath()%&gt;"&gt;View Source Code&lt;/a&gt;
&lt;/div&gt;
&lt;!-- ****** Here is the chart image ****** --&gt;
&lt;%=viewer.renderHTML(response)%&gt;
&lt;/body&gt;
&lt;/html&gt;</code></div></div><br>
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